Question: Solve for $n$ : $n - 15 = -11$
Answer: Add $15$ to both sides: $ \begin{eqnarray} \\ n - 15 &=& -11 \\ \\ {+15} && {+15} \end{eqnarray} $ $ \begin{eqnarray} \hphantom{-15 + n} &\hphantom{=}& \hphantom{-11} \\ n &=& -11 {+ 15} \\ \end{eqnarray} $ Simplify. $ n = 4$